Gilead Sciences (GILD - Get Report) said Tuesday that total product sales will decline sharply in 2017, hurt by falling patient demand and lower net prices for the company's hepatitis C drugs.

The Foster City, Calif.-based biotech company forecast total product sales in the range of $22.5 billion to $24.5 billion, At the midpoint of its new guidance, Gilead is projecting sales to decline by an incredible 22% compared to last year.

Investors were expecting Gilead to issue a down outlook for 2017 but the numbers provided by the company Tuesday were absolutely bleak.

Gilead is forecasting hepatitis C drug sales in 2017 to be in the range of $7.5 billion to $9 billion. At the midpoint, that's a 44% drop off from 2016 sales of $14.8 billion. Investors were prepared for bad news but not to this magnitude.

Shares of Gilead closed Tuesday at $73.13 but then sank 4% in the after-hours market once the company announced its 2017 financial guidance.

If you're looking for a bright spot, Gilead forecast non-hepatitis C product sales to be in the range of $15 billion to $15.5 billion for 2017, comprising mostly of its core HIV drug sales. That's an increase over 2016.

Gilead's HIV foundation isn't crumbling but the rest of the house is in need of serious repair.

Adam Feuerstein writes regularly for TheStreet. In keeping with company editorial policy, he doesn't own or short individual stocks, although he owns stock in TheStreet. He also doesn't invest in hedge funds or other private investment partnerships. Feuerstein appreciates your feedback; click here to send him an email.